What Makes Good AC Compressors Go Bad?

Posted Apr 27, 2012

So you’ve been told that your AC compressor’s “gone bad.” This will likely lead you to a series of questions. Questions like, how did this happen? How much is this going cost me? And what exactly is an AC compressor, anyway?

What Is an AC Compressor?

First things first: The compressor in an air conditioning unit is the “heart” of your system. It is usually located with the condenser and the fan in the outside “box” portion of your AC unit. Contrary to popular perception, AC units don’t add cool air to a space, but rather take heat out of it. The compressor’s role in this process is a critical one.

Refrigerant chemical enters the compressor as a cool gas, and the compressor squeezes it until it is a very hot gas under very high pressure. This allows it to run through the condensing coils and allows the heat to dissipate outside, and eventually evaporate in the end of the cycle through another set of coils, actually removing the heat from the air through this process, blowing it out of the house until the inside is a comfortable temperature.

How Did It Happen?

Compressors are actually very dependable (lasting on average between 12-15 years) so typically, when your AC compressor has gone bad there’s an underlying cause that needs to be addressed lest the problem reemerge even after the unit has been replaced.

There are many ways a compressor can give up the ghost. Nearly all of them are easily preventable with proper, routine maintenance. Some of the usual offenders include:

Refrigerant floodbackThe liquid refrigerant doesn’t completely vaporize in the evaporator, returning into the compressor cylinder and damaging it with runaway pressure. There are many ways this can happen, from refrigerant overcharge to improper settings.

Lack of lubricationAn oil leak, oil trapped in the suction line, and oil pump failure are some of the ways in which the compressor can fail due to oil contamination.

System ContaminationThe causes of compressor failure due to system contamination can include such elements as air, moisture, dirt, and acids which can form with the addition of heat and pressure.

Electrical problemsThe main causes of electrical failure include imbalances in the voltage or current, resulting in overheating and failure.

OverheatingA compressor may overheat if there is not enough suction cooling, lack of condenser cooling, or if there is air in the system, raising both the pressure and temperature.

Costs of AC Compressor Replacement:

Along with being the most important piece of your AC system, the compressor is also the most expensive to replace. Compressor failure often results in a decision to replace the complete system. (Ouch, that hurts.)

A Little Now or a Lot Later

Compressors are expensive to replace, and there are many ways they can go bad. The good news is, most of these causes are preventable with regularly scheduled, preventative maintenance. Regular maintenance can ensure the long life of your compressor, as well as to keep your AC unit healthy and efficient, and your home cool, for years to come.

At SSI, we provide affordable ongoing HVAC maintenance programs and HVAC equipment replacement services to keep your system running strong. What’s more, we offer free second-opinions. If you’ve been told you need a new system or that you have a bad AC compressor and want us to take a second look, just give us a call at (703) 968-0606 and we’ll let you know if we think it should be repaired or replaced.